Selecting particular columns from large datasets (csv) using R Studio?

So I have large number of csv files (100+) in a directory with same structure and column names. The data is in time series and there are approx 30 columns/file. However i only want to aggregate...

08 February 2021 245 5 View

How much pre-PCR dilution of mixed-template DNA extracted from pollen (honey) is appropriate for Metabarcoding?

I'm working on pollen DNA metabarcoding to identify the floral composition of honey. How much pre-PCR dilution of mixed-template DNA extracted from pollen (honey) is appropriate for the...

28 December 2020 9,132 1 View

How to add two vertical and parallel Fresnel reflection coefficients to retrieve overall reflection coefficient for a right hand circular wave?

I have a problem in which a right hand circular polarized wave (GPS wave) encounters an ideal smooth plane obliquely, and then is reflected off that. To solve this kind of problems, the wave is...

28 December 2020 2,271 3 View

Which is better to focus on teaching or research for a good academic life and Why?

Which is better to focus on teaching or research for For a good academic life and Why?

26 December 2020 5,737 9 View

Is ag paste suitable for back contact on silicon wafer? or i should deposit al on the back surface using pvd or plasma sputtering?

Fabricating silicon solar cell

22 December 2020 4,906 7 View

Which renewable source is the best ?

wind hydro solar etc.

21 December 2020 6,360 16 View

Why is light pure energy?

light is pure because the light is the simplest electromagnetic construct but the energy of any object is also of the same kind.

20 December 2020 207 4 View

How to handle Missing Values for Skipped Questions (Systematic Missing) in R ?

10 December 2020 435 4 View

What is the best industrial emulsifier to make silicon oil in water emulsion?

I need to make long-lasting stable emulsions of 6 wt. % percent silicon oil in DI water. The previousely made emulsions using Tween and Span Emulsifiers did not remain stable after a week.

31 October 2020 3,568 3 View

Carbon Emission calculation factors ?

I am thinking about writing a paper on carbon emissions based on electricity consumption data from some buildings. From a research perspective, which factors should i specially focus while...

09 October 2020 4,142 3 View

Can we classify HV and LV lines based on line length?

I have dataset which shows the length of power lines. I need to classify the lines based on the line length. Is there a rule to classify the High voltage (HV) and low voltage (LV) lines based on...

03 March 2021 4,116 4 View

How two melting peaks in DSC of polypropylene can be merged into one crystallization peak?

The figure shows DSC cooling (blue) and 2nd heating (green) curves (step: 10 K/min) for a commercial sample supplied as Atactic Polypropylene (APP). The heating curve illustrates two major...

03 March 2021 5,857 3 View

Irradiation data for JAPAN?

Hi, Could you help me to get the latest (2019, 2020) solar resource data for a particular site in JAPAN? PV GIS and NSRDB data are not in reach to JAPAN, I'm looking for some other database for...

03 March 2021 961 3 View

Is there a powerful system for the security of the systems distributed on IoT systems?

Is there a powerful system for the security of the systems distributed on IoT systems?

02 March 2021 3,858 10 View

What is involved in morphological changes of SEM images of a substance?

In the sem analysis of CaCO3 nanaoparticles, the morphology images showed spherical shaped particles but the proposed morphology for these type of nanoparticles is trigonal. I prepared the...

01 March 2021 1,960 4 View

Precipitate after adding laemmli buffer to protein solution containing Potassium Acetate?

Hi, I am running a size exclusion chromatography experiment with a buffer containing Potassium Acetate as a salt. I analyse these fractions through SDS-PAGE. After boiling my SEC fractions in...

01 March 2021 2,622 3 View

Necessary tube lenght to cool Natural gas in a dry-ice cooling bath?

I have a tank which contains natural gas at 250 Bar and 293 Kelvin. I want to cool the gas in a dry-ice cooling bath to about 195 Kelvin. The gas will flow in a copper-tube through the bath with a...

27 February 2021 8,128 1 View

Exit velocity of natural gas from pressurized tank?

Hi Guys. I'm a mechanical engineer and have a bit trouble, would be very glad if you could help me with my questions. I have a pressurized tank which contains Natural Gas at 200 Bar and 293...

26 February 2021 6,253 3 View

How does an AC-DC power supply Flyback Converter Based USB Charger Model using Matlab/Simulink looks like?

I am required to learn about Flyback converters and I got stuck not knowing to full design of the power supply flyback converter Based USB Charger Model using Simulink, especially the design model...

25 February 2021 5,435 2 View

Sample size determination for non-parametric tests?

How do I run a a priori sample size determination for non-parametric tests, like the Mann-Whitney U-test and the Kruskall-Wallis or other non-parametric tests that accord with the unpaired t-test...

24 February 2021 166 6 View